The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 186
eiver, a is released, and the key falls backto its central position. The keys are often used withoutthe ringing control, in which case the magnet and armatureare omitted. Many different forms of ringing control, or methods of machine ringing, as it is called, are in use, some dependingupon… … on so-called dash-pot principles. The two latter systems enablethe length of time allowed for the ring to be regulated. Themethod shown in Fig. 182 is the invention of Mr W. Aitken. A type of ringing control supplied by the WesternElectric Co. is shown in diagrammatic form in Figs. 256and 259. The…
Telephone
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